Extraction of operating system-specific characteristics via a communication interface

ABSTRACT

Systems and methods for specifying extended descriptor information in a device accessed using a communication interface are disclosed. One method includes transmitting a request to a device from a host computing system, and receiving an extended capability descriptor identifying to the host computing system at least one extended descriptor set stored on the device. The extended capability descriptor identifies a minimum operating system version able to support a corresponding extended descriptor set.

BACKGROUND

The Universal Serial Bus (USB) is a communication interface thatsupports data exchange between a host computer and a wide range ofsimultaneously accessible peripheral devices. The attached peripheraldevices operate using a host-scheduled, token-based protocol. The busallows peripherals to be attached, configured, used, and detached whilethe host and other peripherals are in operation.

USB is defined by a specification that is approved by a committee ofindustry representatives. This USB specification is available from USBImplementers Forum (current Internet URL: www.usb.org). The USBspecification covers all aspects of USB operation, including electrical,mechanical, and communications characteristics. To be called a USBdevice, a peripheral conforms to this specification.

USB device information is typically stored in so-called “descriptors.”Descriptors are used in a USB system to identify the device to a hostsystem, for example so that the host computer can select and executeappropriate software used to interface with the device connected to thathost computer. The host computer transmits control requests to retrievedescriptors from the device. Independent hardware vendors (IHVs) canalso store class and vendor-specific descriptors. However, theflexibility of use of these descriptors, as well as their ensuredcompatibility, is limited. For example, such descriptors are eitherlimited by the types of descriptors included in the specification of thecommunication interface (e.g., USB) with which the device is associated,or else the descriptors may be limited as to their compatibility withvarious host computing systems that may receive such devices.

It is with respect to this general technical environment that theembodiments of the present application are directed.

SUMMARY

In summary, the present disclosure relates to systems and methods forspecifying extended capability descriptor information in a deviceaccessed using a Universal Serial Bus (USB) interface. The extendedcapability descriptor information described herein allows for operatingsystem-specific functionality to be provided by a device, while alsomaintaining compatibility with devices that do not implement extendeddescriptors. In some cases, the extended descriptors are associated witha device, device configuration, or function of a device, therebyallowing a host computing system to address a device at differingscopes. Furthermore, in some embodiments, the extended capabilitydescriptors can be used, for example based on the version or type ofoperating system of the host computing system, with differentconfigurations and/or functionalities, thereby allowing the same deviceto have differing characteristics based on the host computing system towhich it is connected. Additionally, the extended capability descriptorcan identify that the device supports an alternative set of standarddescriptors to be used with a device based, for example, on a minimumoperating system version of the host computing system.

In embodiments, a system includes a programmable circuit and a memorycommunicatively interfaced to the programmable circuit and configured tostore computing instructions. When executed by the programmable circuit,the computing instructions cause the programmable circuit to, inresponse to receiving a request at a device via an interfacecommunicatively connecting the device to a host computing system,communicate a platform capability descriptor to the host computingsystem. The platform capability descriptor includes one or more elementseach identifying a different extended capability descriptor setassociated with the device, at least one of the elements identifying aminimum operating system version able to support a correspondingextended capability descriptor set.

In additional embodiments, a method includes transmitting a request to adevice from a host computing system, and receiving an extendedcapability descriptor identifying to the host computing system at leastone extended descriptor set stored on the device. The extendedcapability descriptor identifies a minimum operating system version ableto support a corresponding extended descriptor set.

In further embodiments, a computer-implemented storage medium isdisclosed that includes computer-executable instructions stored thereon.When executed by a computing device, the instructions cause thecomputing device to perform a method that includes transmitting arequest to a device for one or more descriptors stored at the device,the one or more descriptors including an extended capability descriptor.The request is transmitted from a host computing system via an interfacecommunicatively connecting the device to the host computing system. Themethod also includes receiving the extended capability descriptor at thehost computing system, wherein the extended capability descriptorincludes one or more elements each identifying a different extendedcapability descriptor set associated with the device. At least one ofthe elements identifies a minimum operating system version able tosupport a corresponding extended descriptor set. The method furtherincludes transmitting a second request to the device from the hostcomputing system, the second request corresponding to a request for anextended descriptor set identified based on contents of the extendedcapability descriptor and an operating system of the host computingsystem. The method also includes, in response to the second request,receiving a set of extended descriptors useable to enumerate the devicewith the host computing system, and defining functionality supported bythe operating system of the host computing system.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary system, according to anexample embodiment, including a host computing system and a deviceconnected via a USB interface;

FIG. 2 is a hierarchical diagram of extended capability descriptorsavailable using the methods and systems discussed herein;

FIG. 3 is a logical diagram illustrating an organization of device-levelcharacteristics of an extended capability descriptor set, according toan example embodiment;

FIG. 4 is a logical diagram illustrating an organization ofconfiguration-level characteristics of an extended capability descriptorset, according to an example embodiment;

FIG. 5 is a logical diagram illustrating an organization offunction-level characteristics of an extended capability descriptor set,according to an example embodiment;

FIG. 6 is an example layout of an overall extended capability descriptorset for a composite device and including device- and function-levelfeature descriptors, according to an example embodiment;

FIG. 7 is an example logical layout of a platform capability descriptoruseable to provide identification of one or more extended capabilitydescriptor sets, according to an example embodiment;

FIG. 8 is a flowchart of an example method for extraction ofoperating-system-specific characteristics, according to an exampleembodiment;

FIG. 9 is a detailed flowchart of a method for detecting non-standardcapabilities of a device communicatively connected to a host computingsystem, according to an example embodiment;

FIG. 10 is a simplified block diagram of a computing device with whichpresent embodiments may be practiced;

FIGS. 11A and 11B are simplified block diagrams of a mobile computingdevice with which present embodiments may be practiced;

FIG. 12 is a simplified block diagram of a distributed computing systemin which present embodiments may be practiced.

DETAILED DESCRIPTION

As briefly described above, embodiments of the present disclosure aredirected to systems and methods for specifying extended capabilitydescriptor information in a device accessed using a communicationinterface, for example between a host computing system and a peripheraldevice. The extended capability descriptor information described hereinallows for operating-system-specific functionality or information to beprovided by a device, while also maintaining compatibility with devicesthat do not implement such extended capability descriptors, or whichimplement prior versions of descriptors. Additionally, other types ofconfiguration-specific information can be determined, such as the natureof the host computing system to which a device is connected (e.g., theoperating system or computing architecture of the host system), or thetype of connection used (e.g., a USB standard or low-power connection).Additionally, specific operating system settings and customdevice-specific settings can be provided using such descriptors as well.

In general, USB devices that include operating system (“OS”) descriptorshave been developed. When OS descriptors are integrated into a device,host devices can run operating systems that use those OS descriptors,and can use control requests to retrieve the information. The retrievedinformation is then used to install and configure the USB device withoutrequiring user interaction. However, a current implementation of such OSdescriptors has drawbacks. For example, in some cases, where a USBdevice lacked such an OS descriptor, that device would fail when the OSdescriptor is requested by a host computing system. Furthermore, OSdescriptors are currently unable to provide any specific informationthat is based on identification of differing versions of an operatingsystem of the host device; in other words, current OS descriptors areeither present and able to be accessed by an operating system, or theyare not. Still further, current OS descriptors are defined at aninterface level, rather than at a device level; accordingly, descriptorsfor multifunction devices define features of a particular function,rather than features of the device as a whole. As further discussedbelow, OS descriptors defined according to the present disclosure allowfor scoping of information to an appropriate level, whether that beassociated, for example, with the device, a configuration of the device,or a function included in the device.

Referring now to FIG. 1, a system 100 is shown in which a deviceconnected using a communication interface includes non-standard device,configuration, and function class and subclass codes. Additionally, thesystem includes a host application program and host operating systemthat is able to enumerate non-standard compatible IDs, or non-standardclass and subclass code corresponding to devices. In the embodimentshown, system 100 is compatible with the Universal Serial Bus (USB)specifications. These specifications are available from USB ImplementersForum (current Internet URL: www.usb.org).

System 100 includes a host computing system 102 and a device 114, suchas a USB peripheral device or other peripheral device communicativelyconnected to a host computer (e.g., using the IEEE 1394 serial businterface or a Bluetooth wireless interface). The respectivefunctionality of the computer and peripheral device is embodied in manycases by computer-executable instructions, such as program modules, thatare executed by respective processors. Generally, program modulesinclude routines, programs, objects, components, data structures, etc.that perform particular tasks or implement particular abstract datatypes.

Host computing system 102 is a computing system, such as a desktop,laptop, tablet, or other computing device, such as are described belowand illustrated in FIGS. 10-12. Host computing system 102 has one ormore processors 104 and one or more forms of memory 106 such aselectronic memory, magnetic storage media, optical storage media, orsome other type of data storage. Programs are stored in memory 106 fromwhere they are executed by processor 104. In this example, such programsinclude an operating system 108 such as the MICROSOFT WINDOWS® family ofoperating systems. The operating system 108 provides various systemservices to one or more application programs 110 running on the hostcomputing system 102, and can be any of a variety of types or versionsof an operating system.

In the embodiment shown, the computer also has a USB communicationsdriver and USB port 112. The USB port 112 is supported by operatingsystem 108. To communicate with a device via the USB port, anapplication program 110 makes high-level calls to system servicesprovided by the operating system. The system services take care of lowerlevel communications details, and return requested information to theapplication program.

Device 114 can be, in various embodiments, any of a number of differenttypes of devices such as a data storage device, a digital camera, ascanner, a joystick, game pad, steering unit, mouse, stylus, digitalspeaker, microphone, display device, and the like. In some embodiments,device 114 can be another computing system, such as a mobile phone ortablet computing system. In such embodiments, device 114 has one or moreprocessors 116 and one or more forms of memory 118, including at leastsome form of non-volatile memory 120. In alternative embodiments, thedevice may lack such processors or memory 118. In the example embodimentshown, the device 114 communicatively connects to the host computingsystem 102.

In the embodiment shown, the device 114 has a USB port 126 andcommunicates with host computing system 102 via a USB communicationsinterface 128. The device also optionally has operating logic which isexecuted by processor 116 to detect control actuation and forcommunicating with host computing system 102 across communicationinterface 128.

As is further discussed below, the device 114 responds to requests fromthe host computing system 102 across the communication interface 128.These requests are made using control transfers where setup packets (notshown) are exchanged. In some cases (such as those discussed herein),the device 114 returns descriptors in response to exchanging such setuppackets. The USB Specification defines a number of standard descriptors122, including an extended capability descriptor 123. As used in thepresent disclosure, extended capability descriptor 123 corresponds to astandard descriptor that can include a particular value that indicatesto a host computing system 102 that the device 114 includes one or moreextended descriptors 124. The extended descriptors 124, in turn,correspond to descriptors that are specific to a particular operatingsystem of a host system and not defined in the specification of aparticular communication standard. In the context of a USB interface, anextended capability descriptor would be defined in the USBspecification, which is impartial across operating systems; however, theextended descriptors 124 would not be defined in that specification.Still further in the context of a USB interface, the extended capabilitydescriptor 123, and implicated extended descriptors 124, allow originalequipment manufacturers (“OEMs”) and/or independent hardware vendors(“IHVs”) to store non-standard codes—those specific values representingcapabilities that are not yet defined or supported by the USB DeviceWorking Group (at www.usb.org), for example using logic or storing suchnon-standard codes into non-volatile memory 120 of the device. Moreover,the extended capability descriptor 123 and extended descriptors 124described herein provides a way for a composite device (e.g., a devicehaving more than one function, such as a combinedprinter/scanner/facsimile peripheral device) to specify a group ofinterfaces that comprise a single function, and to allow the hostcomputing system 102 to address either the device as a whole or eachinterface individually.

In embodiments, device 114 supports host-specific device requests toobtain information in accordance with a particular communicationspecification (e.g., USB, Bluetooth, IEEE 1394, etc.). In response tothe request, the peripheral device provides the extended capabilitydescriptor 123 to the host computing system 102. Based on the contentsof the extended capability descriptor 123, the host computer 102 isinformed as to whether the device 114 supports extended descriptors 124that are outside of the set of standard descriptors 122. For example, insome embodiments, the extended capability descriptor 123 can include aparticular value that indicates that extended descriptors 124 aresupported. The extended capability descriptor 123 can also containidentification of one or more sets of such extended descriptors 124, forexample, which can be used with different versions of an operatingsystem of the host computing system 102. The sets of extendeddescriptors can also define, for example primary and alternative sets offunctionality of the device 114, allowing different functionalities tobe selectively enabled for a particular device. Details regarding theextended capability descriptor 123 are discussed in further detail inconnection with FIG. 7; details regarding example loading of extendedcapability descriptor 123 and extended descriptors 124 are providedbelow in connection with FIGS. 8-9.

Referring now to FIG. 2, it is noted that, as further described in thepresent disclosure, as compared to preexisting standard descriptors andexisting extended descriptors, use of the extended capability descriptor123, and the extended descriptors 124 of the present disclosure allowsproperties to be set at varying scope levels. For example, asillustrated in FIG. 2, the extended descriptors 124 can be set at adevice-wide scope 202, a device configuration scope 204, or a specificinterface or function scope 206. Other scopes, such as an endpointscope, could be defined as well. As illustrated in FIGS. 2-6, thedescriptor set is organized as nested groups of descriptor subsets thatcan describe properties specific to a particular scope of the subset inwhich they are contained.

As noted above, extended descriptors 124 can be associated with any ofthe device, device configuration, or function. In the case ofdevice-wide scope 202, the extended descriptors 124 can include featuredescriptions associated with the device and having a device-wide scope202. In the case of device configuration scope 204, the extendeddescriptors 124 can describe functionalities of the device that areavailable depending upon a particular configuration of the device.Similarly, extended descriptors 124 having a function level scope 206can correspond to either functions or function subsets available to asystem that supports the extended capability descriptor 123, as would beavailable at the interface level of the device when implemented with OSdescriptors.

Referring to FIGS. 3-6, and as noted above, extended descriptors 124 areillustrated at the entire device-wide scope 202, device configurationscope 204, and specific interface or function scope 206 (e.g., referredto herein as “feature” descriptors). As seen in FIG. 3, an examplelayout 300 of a set of extended descriptors 124 contains, at the devicelevel (e.g., level 202), a descriptor set header 302 and zero or morefeature descriptors 304 a-m. The feature descriptors 304 a-m areincluded in the set of extended descriptors 124, and apply to the wholedevice regardless of configuration. The set of extended descriptorsfurther includes zero or more configuration subsets 306 a-n that applyto specific device configurations. There are generally one or morefeature descriptors or configuration subset descriptors defined in thedevice level descriptor set. Additionally, other scopes (e.g., endpointlevel scope) could be used as well, with one or more descriptor typesimplemented having that scope.

The descriptor set header 302 includes a descriptor index (wIndex) andoptionally an operating system version identifier defining a minimumoperating system version that supports the descriptor set. Additionally,a size of the descriptor set and version number can be included in theheader 302 as well. The feature descriptors 304 a-m can take a number offorms, as discussed below, and are defined to be the feature descriptorsthat are applicable at the device level 202. The configuration subsets306 a-n correspond to definitions of features applicable at theconfiguration level 204 or in some cases at the function level 206(e.g., if a function subset resides within one of the configurationsubsets 306 a-n, as noted below).

As seen in FIG. 4, the configuration level subset 306 includes a header402 as well as zero or more extended feature descriptors 404 a-m thatapply to a specific USB device configuration (i.e., configuration level204). The configuration level subset 306 also can include within it zeroor more function subsets 406 a-n, each of which applies to specificfunctions within a device (within that configuration).

The configuration level subsets 306 each include a header 402 thatdefines a configuration value (i.e., the particular configuration towhich the descriptor applies) and length of the configuration subset.The corresponding feature descriptors 404 a-m can be any of a variety ofextended capability feature descriptors at the configuration level 204,various types of which are further described below. The function subsets406 a-n define extended functions applicable within that configuration,and are structured as illustrated in FIG. 5.

As seen in FIG. 5, each function subset 406 includes a header 502 thatincludes, among other elements, an interface number of an interface towhich the function applies (useable in multifunction devices to identifya particular interface), as well as a length of the overall functionsubset 406 and the length of the header itself Each function subset 406also includes zero or more feature descriptors 504 a-m, each of whichcorresponds to and defines extended functions applicable within thatfunction. For purposes of the present disclosure, a function is definedas a group of one or more interfaces. A non-composite device would haveone function subset that applies to the interface or interfaces definedfor the configuration. A composite device may have one or more featuredescriptors 504, defining functions. Each function subset generally iswithin a configuration subset, and applies only to that configuration.

Referring now to FIG. 6, an example layout 600 of a descriptor set ofextended descriptors 124 is illustrated, showing the nesting ofdescriptors as outlined in FIGS. 3-5. The example layout 600 illustratesone possible arrangement of an extended descriptor set 124, based on thehierarchical arrangements in FIGS. 3-5, in which a device level featuredescriptor and two function level feature descriptors are shown. As seenin layout 600, a descriptor set header 302 is associated with a featuredescriptor 304, and a configuration level descriptor subset 306. Theconfiguration level descriptor subset 306 includes configuration subsetheader 402, as well as one or more feature descriptors 404 at theconfiguration level (none shown in this example). Within theconfiguration level descriptor subset 306, a plurality of functionsubsets 406 are illustrated as function subsets 406 a-c, each of whichinclude a function subset header 502 and one or more feature descriptors504.

Referring to FIGS. 3-6, it is noted that a variety of descriptor typescan be defined as feature descriptors 304 a-m, 406 a-n, 504 a-m at thedevice-wide scope 202, device configuration scope 204, or function scope206. These descriptor types can include, for example, a featurecompatible or model identifier type, a feature registry property type, afeature CCGP device type, a recovery time type, a preferredconfiguration type, and a model identifier type.

The feature compatible type descriptor defines a compatible device typeidentifier, and can include a string defining a compatible deviceidentifier or sub-compatible device identifier. The compatibleidentifier descriptor can be addressed on a device level 202 or functionlevel 206.

In some example embodiments, in particular those implemented using ahost system having an operating system from among the MICROSOFT WINDOWS®family of operating systems, a feature registry property type descriptoradds per-device or per-function registry values that can be read by aUSB stack or the device's driver. The feature registry propertydescriptor can be addressed on a device-side scope 202 or function scope206, and can include, for example, a type of registry property affected,the name of the registry property, length, and property data to beincluded in the registry (i.e., the registry values to be set). Theproperty data can define the format of the property to be set, includingwhether the property data is null-terminated, little-endian, big-endian,or otherwise formatted (e.g., unicode, integer, freeform etc.). Inalternative embodiments, other types of operating system settings orfeatures could be defined in this descriptor type.

In some other embodiments, a CCGP device feature descriptor can also bedefined, and is used to indicate that the operating system should treatthe device returning such a descriptor as a composite deviceirrespective of a number of interfaces reported by the device. As such,the CCGP device feature descriptor type has device-wide scope.

In still further example embodiments, a recovery time type descriptor isapplied at a device-wide scope 202, and indicates to a host driver aminimum amount of time to recover after a port reset or port resumeoperation for a high, full, or low speed device. This descriptor allowsthe device to recover faster, for example, than the default of 10milliseconds defined in the USB 2.0 specifications. In an exampleembodiment, the descriptor includes a separate setting for minimum timesto recover after a port reset and a port resume; however, the sameminimum time could be used, in alternative embodiments.

In a still further embodiment, a model identifier descriptor typedefines a device model identifier, and can include a unique identifierthat identifies a physical device. The model identifier descriptor canbe addressed on a device-wide scope 202.

Additionally, an alternate set of descriptors can be defined for use andidentified in the extended capability descriptor such that, when thatalternate enumeration vendor-specific control request is received, thehost computing system receives an indication that such alternatedescriptors should be retrieved for use in enumerating the USB device.This can be used, for example, to morph the type of device based on thespecific operating system in use by the host computing system. In suchcases, an alternative set of standard descriptors can be retrieved.Accordingly, the platform capability descriptor can contain informationindicating that for a particular minimum operating system, the devicewants to behave differently. The host computing system will then issue acommand to inform the device which minimum OS version the host isrunning The host can then restart the entire enumeration process,allowing the device to return completely different descriptors. On asubsequent connection of that device, the host computing system willhave cached the information about the alternate enumeration, and afterretrieving the device descriptor, it can immediately issue the command.The host computing system then only has to re-fetch the devicedescriptor, and then continue with the rest of the descriptors. Thiswill improve subsequent enumeration performance in the case of suchalternative descriptors.

In still other embodiments, a preferred configuration index can be usedto indicate which of multiple sets of descriptors should be used whenenumerating a device, allowing the device to enumerate using differentconfiguration descriptors based on, for example, the operating systemversion of the host computing device of whether the device is connectedto a high power or low power USB port. Similar to the alternate set ofdescriptors, the preferred configuration index can be included in thefeature descriptors, and can indicate to the host computing device thata preferred set of additional feature descriptors should be requestedfor enumeration of the device.

In addition to the descriptor types and variations described above,these extended descriptors could be extended to other types of variablefeatures. For example, in some embodiments, descriptors could setdifferent operating system settings or use different preferredconfigurations based upon a computing architecture of a host computingdevice (e.g., whether the host device is an x86-based or ARM-basedcomputing device). For example, whereas in an x86 host system one ormore drivers might be loaded, in a tablet, mobile phone, or otherARM-based host system, the descriptor could provide a link to adownloadable application that provides the USB connectivityfunctionality expected of the device. Other descriptor variations couldbe used as well, such as indicating a particular platform architecturewithin the extended capability descriptor, rather than in one or moreextended descriptors.

It is further noted that, based on the descriptors available for use,various operating-system values and capabilities can be set dependingupon a particular operating system of the host system without requiringany settings provided from a setup information file (i.e., an “INF”file) or a separate update file, thereby improving the “plug-and-play”functionality of the device and enhancing the amount of customization ofthe operation of a USB device when that device is used with differenttypes of host systems. Additionally, the extended capability descriptorsprovided herein do not interfere with existing extended capabilitydescriptor functionality that is limited to a per-function (i.e.,per-interface) basis, and which resulted in some device compatibilityissues. Host devices implementing an operating system that supports theextended descriptors of the present disclosure will therefore bothprovide backward compatibility for devices that include those previoustypes of descriptors as well as the improved compatibility with andcustomization of USB devices to which they are interconnected.

Referring now to FIG. 7 an example logical layout of an extendedcapability descriptor 700 is shown. The extended capability descriptor700 is useable to allow a USB device to identify to a host computingsystem that the extended capability descriptor sets of the presentdisclosure are supported by that particular device. In particular, theextended capability descriptor 700 provides a header 702 and one or moredescriptor set identifiers 704 a-c.

The header 702 generally includes descriptor type, length, andcapability type information, as well as a particular code identifyingthe device as supporting the type of extended descriptors provided forherein. Based on that code (e.g., a universally unique identifier, orUUID, or other type of value), a receiving host system (e.g., hostcomputing system 102 of FIG. 1) can determine whether it is capable ofusing the extended descriptors included in the device. The accompanyingone or more descriptor set identifiers can include, among otherelements, an operating system version identifier used to identify aminimum operating system level able to support a particular extendeddescriptor set, a size of the corresponding descriptor set, and a vendorcode used to identify a particular extended descriptor set. In someembodiments, each of the one or more descriptor set identifiers can alsoinclude an alternate enumeration identifier, indicative of whether thedevice should, when the alternate enumeration control transfer isreceived, return non-default descriptors for the communication interface(e.g., USB). Such information, and in particular the vendor code, can beused by a host computing device to issue one or more vendor-specificcontrol requests to the device to obtain corresponding extendeddescriptor sets, if that host device has an adequately up to dateoperating system identified by the operating system identifier. Detailsregarding a method of requesting the extended capability descriptor 700and associated extended descriptor sets are provided below, and shown inFIGS. 8-9.

It is noted that, because the extended capability descriptor 700 itselfis intended to be supported in the USB specification (although theunique code defining the extended capability is not), retrieving anextended capability descriptor 700 from another device that does notsupport the extended descriptors will not cause that device tofreeze/hang, and therefore reliable operation across all USB devices canbe improved. Rather, based on the value retrieved in the extendedcapability descriptor 700, one or more extended descriptors can berequested and used to enumerate the device with the host computingsystem, using an operating system-specific set of descriptors, oralternate descriptors that can define the device to the host computingsystem in a different manner than would otherwise be provided by thedefault set of standard descriptors. Beyond the flexibility such anarrangement provides, it also ensures compatibility with devices that donot support extended descriptors or alternate configurations, since suchdescriptors would be requested only upon a determination that thosedescriptors are present in the device (as indicated by the extendedcapability descriptor 700).

Referring now to FIGS. 8-9, additional details are described regarding aprocess by which an extended capability descriptor and associatedextended descriptor sets may be requested from a device via a USBinterface. In embodiments, the method of FIG. 8 may be performed by ahost computing device (e.g., host computing system 102). In particular,FIG. 8 shows a top-level method of an example procedure for obtainingextended descriptor sets according to the present disclosure. Generally,the method 800 includes requesting 802, via a USB interface, a standarddescriptor, which includes one or more extended capability descriptors.The request can be transmitted from a host computing system to a device.Among the standard descriptors, an extended capability descriptor can beincluded, for example, within a set of Binary Device Object Store (BOS)device capability descriptors included within the USB standards. Theextended capability descriptor is received, for example alongside theother descriptors included in the requested descriptor set at operation804. This receipt of standard descriptors occurs, for example, at thehost computing system.

The standard descriptors include one or more extended capabilitydescriptors, which in turn may include operating system versiondefinitions. In embodiments, the host computing system then assesses theextended capability descriptor to determine if the extended descriptorsof the present disclosure are supported, for example based on a codeincluded within the extended capability descriptor.

Next, method 800 proceeds to operation 806, wherein one or more controlrequests are made for an extended descriptor set. In embodiments, thehost computing device can issue one or more device requests to thedevice via a USB interface, to request one or more of the newly-definedextended descriptors in an extended descriptor set (e.g., using avendor-specific control request, as discussed below in FIG. 9). Acontrol transfer is a data structure that is conveyed from the host tothe peripheral device. A control transfer contains the following fields:

-   -   bmRequestType—a mask field indicating (a) the direction of data        transfer in a subsequent phase of the control transfer; (b) a        request type (standard, class, vendor, or reserved); and (c) a        recipient (device, interface, endpoint, or other). The primary        types of requests specified in the “request type” field are the        “standard” and “vendor” types, which will be discussed below.    -   bRequest—a request code indicating one of a plurality of        different commands to which the device is responsive.    -   wValue—a field that varies according to the request specified by        bRequest.    -   wIndex—a field that varies according to request; typically used        to pass an index or offset as part of the specified request.    -   wLength—number of bytes to transfer if there is a subsequent        data stage.

All USB devices are designed to support and respond to “standard”requests supported in the USB specification, and referred to herein as“USB-specific” requests. It is noted that when extended descriptors areapplied using other communications interfaces, a set of standard requestand standard descriptors may change, according to the specification forthat alternative interface.

In USB-specific requests, the request type portion of the bmRequestTypefield contains a predefined value indicative of the “standard” requesttype. USB devices can optionally support “vendor” requests—referred toherein as “device-specific” requests. In a device-specific request, therequest type portion of the bmRequestType field contains a predefinedvalue to indicate a “vendor” request type. In the case ofdevice-specific requests, the USB specification does not assign requestcodes, define the meanings of wValue and wIndex, or define the format ofreturned data. Rather, each device has nearly complete control over themeaning, functionality, and data format of device-specific requests.Specifically, the vendor or designer of a device can define its ownrequests and assign device-specified request codes to them. This allowsdevices to define their own device requests for use by host computers,and provides flexibility for manufacturers of peripherals.

In the context of the present disclosure, based on a previous request ofan extended capability descriptor, the request, and in particular thewValue and wIndex fields, can be populated with a particular set ofvalues. Specifically, the wIndex value can be set to a known index fordescriptors supported by the new extended capability descriptors of thepresent disclosure. It is noted that generally, for each standardUSB-specific request code, the USB specification sets forth the meaningsof wValue and wIndex, as well as the format of any returned data.Additionally, for previous versions of the present extended capabilitydescriptor arrangement, a predetermined wIndex may be used withoutverifying support for such values, leading to a possibility that thedevice receiving the request will hang or otherwise react with an errorto an index value that is undefined in that device.

At operation 808, the descriptors in the extended descriptor set (e.g.,device, configuration, and/or function descriptors) are received. Inembodiments, the host computing system can receive the one or moreextended descriptors from the device. The host computing system can usethose extended descriptors to define operation of the device, installany drivers, and otherwise enumerate the device. It is noted that thehost computing system can repeat the vendor-specific control request asdesired to obtain different information from the device as needed.

Referring now to FIG. 9, additional details regarding the request anddetermination of compatibility with the extended descriptors of thepresent disclosure are provided. In particular, in method 900, a requestis transmitted at operation 902 for an extended capability descriptor,for example as part of a BOS descriptor set. This request can betransmitted, for example, from host computing system to the device. Therequest is received, and the corresponding extended capabilitydescriptor is returned at operation 904 (e.g., along with otherdescriptors in the BOS descriptor set). If the returned set ofcapability descriptors lacks the extended capability descriptor, or ifthe returned extended capability descriptor lacks any value thatindicates support for the extended descriptors of the presentdisclosure, operation 906 determines that the host computing system canconfigure descriptor requests that are not operating system specific.Accordingly, at operation 908, descriptor requests in this case wouldrevert to existing descriptor request process, This can include arequest for only standard descriptors, or a request for extendeddescriptors that are not supported or identified using the extendedcapability descriptor (e.g., in a prior version of the extendeddescriptors described herein). Otherwise, if the extended capabilitydescriptor includes a code (e.g., UUID) that indicates support for theextended descriptors, a request for extended descriptor sets can begenerated at operation 910, for example by a host computing system. Thiscan include one or more extended descriptor sets that each correspondsto a different minimum operating system level supported by the device.

At operation 912, a vendor-specific control request is transmitted thatincludes a bRequest value identifying a vendor code that corresponds tothe supported minimum operating system requirements. For example, thevendor-specific control request can be sent from the host computingsystem to the device. A compatible device receives the request atoperation 914, and is configured to respond to such a request byreturning an extended descriptor. The extended descriptor can be, forexample, any of the descriptor types discussed above in connection withFIGS. 3-6.

More specifically, at operation 916 the vendor-specific control requestis received. For example, based on such a request, a device determineswhether the vendor-implemented request value corresponds to the valueidentified in the vendor-specific control request (e.g., the bRequestvalue defined in the vendor code in the extended capability descriptor.The requested one or more extended descriptors are then returned inresponse to the request. At this point, in the embodiment shown, theextended capability descriptor set is received at operation 918, whichcan include, for example, one or more extended descriptors received by ahost computing device.

In a possible implementation of this system, the device request is usedto request one of a plurality of available descriptors from the device.The bRequest field of the host-specific request for extended descriptorsindicates which of the plurality of available extended descriptors areto be returned. The device returns the descriptor referred to bybRequest.

Referring to FIGS. 1-9 generally, the techniques described above allowan operating system designer to specify extended descriptors thatdevices can implement to provide additional data about themselves-datathat is not directly addressed by the USB specification. For example,the techniques described above allow an operating system to specify theextended descriptor 123 and extended descriptors 124 of FIG. 1. Theoperating system of a host system then uses the extended descriptors toidentify features of a device that are not supported by thecommunication interface (e.g., USB) that is used by the device thatsupport non-standard USB DWG class codes and/or subclass codes todetermine one or more device drivers to control the devices.

In addition to the above, the extended capability descriptors andextended descriptors of the present disclosure provide furtheradvantages over existing extended descriptors. In particular, by using arequest of an existing, defined descriptor included in the USBspecification (i.e., the extended capability descriptor), thatdescriptor will advertise whether operating system-specific capabilitiesare supported that allow for device, configuration, and function levelcapabilities to be defined. This ensures backward compatibility (i.e.,it will not cause unexpected conduct by USB devices not supporting theextended capabilities). In addition, the extended descriptors discussedherein allow devices to describe themselves on a device-wide basis,rather than on a per function basis. Additionally, using the extendedcapability descriptors of the present disclosure, the device can exposea least common denominator set of features to each host system to whichit is connected, while providing extended functionality to supportedhost devices.

Finally, although the present disclosure describes the extendedcapability descriptors and extended descriptors as directed to usewithin a USB interface, it is recognized that in some embodiments, theextended capability descriptor and extended descriptors are not solimited. For example, the extended capability descriptor and extendeddescriptors can be included in one or more alternative interface types,such as a PCI, Bluetooth, or other type of wired or wireless interface.

The embodiments and functionalities described herein may operate via amultitude of computing systems such as the host computing system 102 anddevice 114 described above with reference to FIG. 1, including wired andwireless computing systems, mobile computing systems (e.g., mobiletelephones, tablet or slate type computers, laptop computers, etc.). Inaddition, the embodiments and functionalities described herein mayoperate over distributed systems (e.g., cloud-based computing systems),where application functionality, memory, data storage and retrieval andvarious processing functions may be operated remotely from each otherover a distributed computing network, such as the Internet or anintranet. User interfaces and information of various types may bedisplayed via on-board computing device displays or via remote displayunits associated with one or more computing devices. For example userinterfaces and information of various types may be displayed andinteracted with on a wall surface onto which user interfaces andinformation of various types are projected. Interaction with themultitude of computing systems with which embodiments of the disclosuremay be practiced include, keystroke entry, touch screen entry, voice orother audio entry, gesture entry where an associated computing device isequipped with detection (e.g., camera) functionality for capturing andinterpreting user gestures for controlling the functionality of thecomputing device, and the like. FIGS. 10 through 12 and the associateddescriptions provide a discussion of a variety of operating environmentsin which embodiments of the invention may be practiced. However, thedevices and systems illustrated and discussed with respect to FIGS. 10through 12 are for purposes of example and illustration and are notlimiting of a vast number of computing device configurations that may beutilized for practicing embodiments of the disclosure, described herein.

FIG. 10 is a block diagram illustrating example physical components of acomputing device 1000 with which embodiments of the disclosure may bepracticed. The computing device components described below may besuitable for the computing devices described above, for example, thehost computing system 102 or device 114 of FIG. 1. In a basicconfiguration, computing device 1000 may include at least one processingunit 1002 and a system memory 1004. Depending on the configuration andtype of computing device, system memory 1004 may comprise, but is notlimited to, volatile (e.g. random access memory (RAM)), non-volatile(e.g. read-only memory (ROM)), flash memory, or any combination. Systemmemory 1004 may include operating system 1005 and one or moreprogramming modules 1006, which are suitable for running applications,such as a client application or server applications. Operating system1005, for example, may be suitable for controlling the operation ofcomputing device 1000. Furthermore, embodiments of the disclosure may bepracticed in conjunction with a graphics library, other operatingsystems, or any other application program and is not limited to anyparticular application or system. This basic configuration isillustrated in FIG. 10 by those components within a dashed line 1008.

Computing device 1000 may have additional features or functionality. Forexample, computing device 1000 may also include additional data storagedevices (removable and/or non-removable) such as, for example, magneticdisks, optical disks, or tape. Such additional storage is illustrated inFIG. 10 by a removable storage 1009 and a non-removable storage 1010.

As stated above, a number of program modules and data files may bestored in system memory 1004, including operating system 1005. Whileexecuting on processing unit 1002, programming modules 1006 may performprocesses including, for example, one or more of the stages of themethods discussed in FIGS. 8-9. The aforementioned process is anexample, and processing unit 1002 may perform other processes. Otherprogramming modules that may be used in accordance with embodiments ofthe present disclosure may include electronic mail and contactsapplications, word processing applications, spreadsheet applications,database applications, slide presentation applications, drawing orcomputer-aided application programs, etc.

Generally, consistent with embodiments of the disclosure, programmodules may include routines, programs, components, data structures, andother types of structures that may perform particular tasks or that mayimplement particular abstract data types. Moreover, embodiments of thedisclosure may be practiced with other computer system configurations,including hand-held devices, multiprocessor systems,microprocessor-based or programmable consumer electronics,minicomputers, mainframe computers, and the like. Embodiments of thedisclosure may also be practiced in distributed computing environmentswhere tasks are performed by remote processing devices that are linkedthrough a communications network. In a distributed computingenvironment, program modules may be located in both local and remotememory storage devices.

Furthermore, embodiments of the disclosure may be practiced in anelectrical circuit comprising discrete electronic elements, packaged orintegrated electronic chips containing logic gates, a circuit utilizinga microprocessor, or on a single chip containing electronic elements ormicroprocessors. For example, embodiments of the disclosure may bepracticed via a system-on-a-chip (SOC) where each or many of thecomponents illustrated in FIG. 10 may be integrated onto a singleintegrated circuit. Such an SOC device may include one or moreprocessing units, graphics units, communications units, systemvirtualization units and various application functionality all of whichare integrated (or “burned”) onto the chip substrate as a singleintegrated circuit. When operating via an SOC, the functionality ofserver applications 1020 or client applications 1022 may be implementedvia application-specific logic integrated with other components of thecomputing device 1000 on the single integrated circuit (chip).Embodiments of the disclosure may also be practiced using othertechnologies capable of performing logical operations such as, forexample, AND, OR, and NOT, including but not limited to mechanical,optical, fluidic, and quantum technologies. In addition, embodiments ofthe disclosure may be practiced within a general purpose computer or inany other circuits or systems.

The term computer readable media as used herein may include computerstorage media. Computer storage media may include volatile andnonvolatile, removable or non-removable media implemented in any methodor technology for storage of information, such as computer readableinstructions, data structures, or program modules. System memory 1004,removable storage 1009, and non-removable storage 1010 are all computerstorage media examples (i.e., memory storage). Computer storage mediamay include RAM, ROM, electrically erasable read-only memory (EEPROM),flash memory or other memory technology, CD-ROM, digital versatile disks(DVD) or other optical storage, magnetic cassettes, magnetic tape,magnetic disk storage or other storage devices, or may include any otherarticle of manufacture which can be used to store information and whichcan be accessed by computing device 1000. Any such computer storagemedia may be part of device 1000. As described herein, computer storagemedia does not include communication media (defined hereinafter), or anypropagated data signals or modulated data signals. Computing device 1000may also have input device(s) 1012 such as a keyboard, a mouse, a pen, asound input device, a touch input device, etc. Output device(s) 1014such as a display, speakers, a printer, etc. may also be included. Theaforementioned devices are examples and others may be used.

The term computer readable media as used herein may also includecommunication media. Communication media may be embodied by computerreadable instructions, data structures, program modules, or other datain a modulated data signal, such as a carrier wave or other transportmechanism, and includes any information delivery media. The term“modulated data signal” may describe a signal that has one or morecharacteristics set or changed in such a manner as to encode informationin the signal. By way of example, and not limitation, communicationmedia may include wired media such as a wired network or direct-wiredconnection, and wireless media such as acoustic, radio frequency (RF),infrared, and other wireless media. Computing device 1000 may includecommunication connections 1016 allowing communications with othercomputing devices 1018. Examples of suitable communication connections1016 include, but are not limited to, RF transmitter, receiver, and/ortransceiver circuitry; universal serial bus (USB), parallel, or serialports, and other connections appropriate for use with the applicablecomputer readable media. In connection with the present disclosure, itis noted that the operating system 1005 of computing device 1000 can beone of a number of versions of operating systems, and may, in suchcases, enable differing sets of functionality in the other computingdevices 1018, such as through use of an extended configurationdescriptor 1024 and associated extended descriptors 1025 stored in orreceived by the system memory 1004, removable storage 1009, ornon-removable storage 1010 as well as existing platform capabilitydescriptor values managed by the other computing devices 1018.

FIGS. 11A and 11B illustrate a suitable mobile computing environment,for example, a mobile computing device 1100, such as a smart phone, atablet personal computer, a laptop computer, and the like, with whichembodiments of the disclosure may be practiced. With reference to FIG.11A, an example mobile computing device 1100 for implementing theembodiments is illustrated. In a basic configuration, mobile computingdevice 1100 is a handheld computer having both input elements and outputelements. Input elements may include touch screen display 1105 and inputbuttons 1110 that allow the user to enter information into mobilecomputing device 1100. Mobile computing device 1100 may also incorporatean optional side input element 1115 allowing further user input.Optional side input element 1115 may be a rotary switch, a button, orany other type of manual input element. In alternative embodiments,mobile computing device 1100 may incorporate more or less inputelements. For example, display 1105 may not be a touch screen in someembodiments. In yet another alternative embodiment, the mobile computingdevice is a portable phone system, such as a cellular phone havingdisplay 1105 and input buttons 1110. Mobile computing device 1100 mayalso include an optional keypad 1135. Optional keypad 1135 may be aphysical keypad or a “soft” keypad generated on the touch screendisplay.

Mobile computing device 1100 incorporates output elements, such asdisplay 1105, which can display a graphical user interface (GUI). Otheroutput elements include speaker 1125 and LED 1120. Additionally, mobilecomputing device 1100 may incorporate a vibration module (not shown),which causes mobile computing device 1100 to vibrate to notify the userof an event. In yet another embodiment, mobile computing device 1100 mayincorporate a headphone jack (not shown) for providing another means ofproviding output signals.

Although described herein in combination with mobile computing device1100, in alternative embodiments the disclosure is used in combinationwith any number of computer systems, such as in desktop environments,laptop or notebook computer systems, multiprocessor systems,micro-processor based or programmable consumer electronics, network PCs,mini computers, main frame computers and the like. Embodiments of thedisclosure may also be practiced in distributed computing environmentswhere tasks are performed by remote processing devices that are linkedthrough a communications network in a distributed computing environment;programs may be located in both local and remote memory storage devices.

FIG. 11B is a block diagram illustrating components of a mobilecomputing device used in one embodiment, such as the computing deviceshown in FIG. 11A. That is, mobile computing device 1100 can incorporatesystem 1102 to implement some embodiments. For example, system 1102 canbe used in implementing a “smart phone” that can run one or moreapplications similar to those of a desktop or notebook computer such as,for example, browser, e-mail, scheduling, instant messaging, and mediaplayer applications. In some embodiments, system 1102 is integrated as acomputing device, such as an integrated personal digital assistant (PDA)and wireless phone.

One or more application programs 1166 may be loaded into memory 1162 andrun on or in association with operating system 1164. Examples ofapplication programs include phone dialer programs, e-mail programs,personal information management (PIM) programs, word processingprograms, spreadsheet programs, Internet browser programs, messagingprograms, and so forth. Such application programs can also includeapplication programs that assist in communicating with peripheraldevices, such as device 114 of FIG. 1, above, via a peripheral deviceport. Accordingly, application programs 1166 can be used to implementdiffering functionality sets based on different extended capabilitydescriptor sets supported by different versions of the operating system1164.

System 1102 also includes non-volatile storage 1168 within memory 1162.Non-volatile storage 1168 may comprise computer storage media and may beused to store persistent information that should not be lost if system1102 is powered down. Applications may be loaded into memory 1162 andrun on the device 1100, including the various client and serverapplications described herein. In addition, in the example shown, one ormore OS descriptors 1169, including an extended capability descriptor orset of extended descriptors, as described above, could be includedwithin the memory 1162.

System 1102 has a power supply 1170, which may be implemented as one ormore batteries. Power supply 1170 might further include an externalpower source, such as an AC adapter or a powered docking cradle thatsupplements or recharges the batteries.

System 1102 may also include a radio 1172 that performs the function oftransmitting and receiving radio frequency communications. Radio 1172facilitates wireless connectivity between system 1102 and the “outsideworld”, via a communications carrier or service provider. Transmissionsto and from radio 1172 are conducted under control of the operatingsystem 1164. In other words, communications received by radio 1172 maybe disseminated to application programs 1166 via operating system 1164,and vice versa.

The embodiment of system 1102 shown includes two types of notificationoutput devices; light emitting diode (LED) 1120 that can be used toprovide visual notifications and an audio interface 1174 that can beused with speaker 1125 to provide audio notifications. These devices maybe directly coupled to power supply 1170 so that when activated, theyremain on for a duration dictated by the notification mechanism eventhough processor 1160 and other components might shut down forconserving battery power. LED 1120 may be programmed to remain onindefinitely until the user takes action to indicate the powered-onstatus of the device. Audio interface 1174 is used to provide audiblesignals to and receive audible signals from the user. For example, inaddition to being coupled to speaker 1125, audio interface 1174 may alsobe coupled to a microphone to receive audible input, such as tofacilitate a telephone conversation. In accordance with embodiments ofthe present disclosure, a microphone may also serve as an audio sensorto facilitate control of notifications, as will be described below.System 1102 may further include video interface 1176 that enables anoperation of on-board camera 1130 to record still images, video stream,and the like.

A mobile computing device implementing system 1102 may have additionalfeatures or functionality. For example, the mobile computing device 1100may also include additional data storage devices (removable and/ornon-removable) such as, magnetic disks, optical disks, or tape.

Data/information generated or captured by the mobile computing device1100 and stored via the system 1102 may be stored locally on the mobilecomputing device 800, as described above, or the data may be stored onany number of storage media that may be accessed by the device via aradio 1172 or via a wired connection between the mobile computing device1100 and a separate computing device associated with the mobilecomputing device 1100, for example, a server computer in a distributedcomputing network, such as the Internet. As should be appreciated suchdata/information may be accessed via the mobile computing device 1100via the radio 1172 or via a distributed computing network. Similarly,such data/information may be readily transferred between computingdevices for storage and use according to well-known data/informationtransfer and storage means, including electronic mail and collaborativedata/information sharing systems.

FIG. 12 illustrates a system architecture for providing a remoteapplication, such as a downloadable driver or web application useablefor USB interface configuration, to one or more client devices, asdescribed above. Content developed, interacted with or edited inassociation with the remote application may be stored. For example,various documents may be stored using directory services 1222, webportals 1224, mailbox services 1226, instant messaging stores 1228 andsocial networking sites 1230. The remote application may use any ofthese types of systems or the like for enabling data utilization, asdescribed herein. A server 1220 may provide the remote application toclients. As one example, server 1220 may be a web server providing thehost application 1020, over the web. Server 1220 may provide the remoteapplication over the web to clients through a network 1215. Examples ofclients that may access a remote application may include any generalpurpose personal computer 1202, a tablet computing device 1204 and/ormobile computing device 1206 such as smart phones, each of which mayinclude a USB or other analogous interface. Any of these devices mayobtain content from the store 1216. For example, the downloadable driveror web application can be provided to a host computing system, such ashost computing system 102 of FIG. 1, which may be implemented as any ofgeneral purpose personal computer 1202, a tablet computing device 1204and/or mobile computing device 1206.

Embodiments of the present disclosure, for example, are described abovewith reference to block diagrams and/or operational illustrations ofmethods, systems, and computer program products according to embodimentsof the disclosure. The functions/acts noted in the blocks may occur outof the order as shown in any flowchart. For example, two blocks shown insuccession may in fact be executed substantially concurrently or theblocks may sometimes be executed in the reverse order, depending uponthe functionality/acts involved.

While certain embodiments of the disclosure have been described, otherembodiments may exist. Further, the disclosed methods' stages may bemodified in any manner, including by reordering stages and/or insertingor deleting stages, without departing from the disclosure.

The description and illustration of one or more embodiments provided inthis application are not intended to limit or restrict the scope of theinvention as claimed in any way. The embodiments, examples, and detailsprovided in this application are considered sufficient to conveypossession and enable others to make and use the best mode of claimedinvention. The claimed invention should not be construed as beinglimited to any embodiment, example, or detail provided in thisapplication. Regardless of whether shown and described in combination orseparately, the various features (both structural and methodological)are intended to be selectively included or omitted to produce anembodiment with a particular set of features. Having been provided withthe description and illustration of the present application, one skilledin the art may envision variations, modifications, and alternateembodiments falling within the spirit of the broader aspects of theclaimed invention and the general inventive concept embodied in thisapplication that do not depart from the broader scope.

1. A device comprising: a communication interface; a memory configuredto store a plurality of descriptors accessible by a host computingsystem communicatively connected to the communication interface, theplurality of descriptors including: an extended capability descriptorincluding an identification of a minimum operating system version ableto support an extended descriptor set; and one or more extendeddescriptors included in the extended descriptor set, the one or moreextended descriptors recognizable to a host computing system executingat least the minimum operating system version and useable to enumeratethe device thereon.
 2. The device of claim 1, wherein the extendedcapability descriptor is included in a plurality of Binary Device ObjectStore (BOS) descriptors.
 3. The device of claim 1, wherein the extendedcapability descriptor includes a header and at least one element,wherein the at least one element of the extended capability descriptordefines the minimum operating system version.
 4. The device of claim 3,wherein the extended capability descriptor includes at least one elementindicating the existence of an alternate enumeration of the device to ahost computing system.
 5. The device of claim 3, wherein the device isconfigured to: receive a control request via a USB interface to obtainan extended descriptor set including the one or more extendeddescriptors, the control request based on the extended capabilitydescriptor and an operating system version of the host computing system;and provide, in response to the control request, an extended descriptorset including the one or more extended descriptors definingfunctionality of the device to be enumerated at the host computingsystem.
 6. The device of claim 5, wherein the extended descriptor setdefines a set of extended descriptors supported by a host computingsystem having a minimum operating system version.
 7. The device of claim5, wherein the one or more extended descriptors in the extendeddescriptor set include a descriptor applicable to an entire device. 8.The device of claim 7, wherein the one or more extended descriptors inthe extended descriptor set further include a descriptor applicable to adevice configuration.
 9. The device of claim 7, wherein the zero or moreextended descriptors in the extended descriptor set further include adescriptor applicable to a function provided by the device.
 10. Thedevice of claim 5, wherein the one or more descriptors have a pluralityof different descriptor types, the descriptor types selected from agroup of descriptor types consisting of: a feature registry propertytype; a feature CCGP device type; a feature compatible ID type; arecovery time type; a preferred configuration type; and a modelidentifier type.
 11. The system of claim 5, wherein the device comprisesa multifunction peripheral device having a plurality of functions, andwherein the extended capability descriptor set includes one or moredescriptors defining features of the entire device and applicable toeach of the plurality of functions.
 12. A method comprising:transmitting a request to a device from a host computing system;receiving an extended capability descriptor identifying to the hostcomputing system at least one extended descriptor set stored on thedevice, wherein the extended capability descriptor identifies a minimumoperating system version able to support a corresponding extendeddescriptor set.
 13. The method of claim 12, further comprising:determining whether the extended capability descriptor indicates thatthe device supports non-standard capabilities supported by an operatingsystem version of the host computing system; and transmitting a controlrequest to the device via a USB interface to obtain an extendeddescriptor set supported by the device, the control request including avendor code based on the extended capability descriptor and an operatingsystem version of the host computing system.
 14. The method of claim 12,further comprising: determining whether the extended capabilitydescriptor indicates that the device supports an alternate enumeration;and transmitting a control request associated with an alternatedescriptor set corresponding to the alternate enumeration.
 15. Themethod of claim 12, wherein the extended capability descriptor includesa plurality of elements, each element including an identification of aminimum operating system version able to support a correspondingextended descriptor set, a length of the corresponding extendeddescriptor set, and a vendor code associated with the device.
 16. Themethod of claim 12, further comprising receiving, in response to acontrol request, an extended descriptor set including a set ofnon-standard descriptors defining capabilities of the device availableto the host computing system based on the operating system version. 17.The method of claim 16, wherein the extended descriptor set includes atleast one descriptor having a device-wide scope.
 18. The method of claim17, wherein the extended descriptor set includes a second at least onedescriptor at a device configuration level.
 19. The method of claim 12,wherein the extended descriptor set includes a descriptor having a hostarchitecture descriptor type, the host architecture type defining acapability available to the host computing device dependent upon acomputing architecture of the host computing device.
 20. A computerstorage medium including computer-executable instructions stored thereonwhich, when executed by a computing device, cause the computing deviceto perform a method comprising: transmitting a request to a device forone or more descriptors stored at the device, the one or moredescriptors including an extended capability descriptor, the requesttransmitted from a host computing system via an interfacecommunicatively connecting the device to the host computing system;receiving the extended capability descriptor at the host computingsystem, wherein the extended capability descriptor includes one or moreelements each identifying a different extended capability descriptor setassociated with the device, at least one of the elements identifying aminimum operating system version able to support a correspondingextended descriptor set; transmitting a second request to the devicefrom the host computing system, the second request corresponding to arequest for an extended descriptor set identified based on contents ofthe extended capability descriptor and an operating system of the hostcomputing system; and in response to the second request, receiving a setof extended descriptors useable to enumerate the device with the hostcomputing system and defining functionality supported by the operatingsystem of the host computing system.